I'm curious if anyone knows about any potential anti-depressant qualities of various teas or tisanes. I'm googling and not finding much, other than jasmine as a fragrance seems to have some benefit... but no word about it in teas.

Well, there was some talk about it in the tea world a year or so ago. I seem to remember something called Theanine that is supposed to reduce anxiety and work in sort of the opposite direction of the the caffeine.

L-Theanine would do more to counter anxiety than depression...but the two often go hand in hand for many people.

In really simplified terms, L-theanine sort of works like ADD medication in that it relaxes, but allows you to maintain a focus. It *may* reduce the uptake of another amino acid, glutamate (the main guy behind the 'umami' taste, incidentally), which may in turn change the uptake of things like serotonin and dopamine, and *that* could result in anti-depressant like qualities.

But...I'm no chemist. I sort of occasionally read articles. My end of science was more focused on evolution/ecology. I am not qualified in any way to say anything of consequence in this matter. Scruff's earned a piece of paper that says he is skilled in neuroscience, though. Maybe if you ask nicely, he'll weigh in.

Thank goodness for wikipedia! L-Theanine increases GABA (which basically has the opposite effect on the brain as glutamate), serotonin, and dopamine levels in the brain (link). Other things that increase GABA levels include alcohol and benzodiazapines (e.g. valium), which is probably the explanation for why tea has calming effects. Selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed as anti-depressants, and essentially increase serotonin levels. Dopamine is another neurotransmitter associated with mood. Another drug which increases dopamine levels is cocaine, which may explain Salsero sometimes. (bwahahaha )

So, ironically, while it could be considered a "depressant" (as alcohol and benzodiazapines are), it may have some anti-depressant (in the clinical sense) properties. That said, I don't know enough about the compound to say for certain whether or not it acts like an anti-depressant, or whether the amount normally consumed in tea is enough to have such an effect on the brain.

Of course, the usual disclaimer applies; be sure to check with your doctor before using tea as a medication.

As far as umami and glutamate/all amino acids goes...I need to do some reading. From an article I read last year (and I think was published in 04 or 05...can't remember) I was under the impression that the receptors in the mouth are pretty specific to glutamate and glutamic acid, but the Umami Information Center mentions that "umami is a savoury taste imparted by glutamate and ribonucleotides, including inosinate and guanylate."

Moar readings for me. Yay. Anything to postpone a summer immersion in Old English texts.

That last one is particularly good. I wish I had time to really read it through now...alas, no. Bookmark!

Anyone happen to know just how much l-theanine is actually in a cup of tea? I can't imagine anyone could actually drink enough tea to notice anti-depressant effects on par with the current pharmacopeia. But yeah...standard Mary disclaimer...I need more research.

On another note, I would bet that caffeine would have some effect on depression, and Tyrosine most definitely would. Tyrosine helps to make better use of dopamine and increase brain function (generally making you more awake, alert, focused, etc.). I sometimes take a Tyrosine supplement on days that I'm particularly tired or under the weather

Mary R wrote:Back to the nominal topic...anyone happen to know just how much l-theanine is actually in a cup of tea? I can't imagine anyone could actually drink enough tea to notice anti-depressant effects on par with the current pharmacopeia. But yeah...standard Mary disclaimer...I need more research.

It would, of course, depend entirely on the tea. Teas that are thick and sweet (like Taiwan high-mountains) seem to be high in L-Theanine. My body craved it with a vengence and drew me almost exclusively to these thick and sweet teas until I started taking Theanine supplements and a GABA agonist med.

I do have a science paper on amino acids in tea that I paid for if you and Scruff would like to take a look

Yes, theanine and glutamate are very similar, structurally. However, so are GABA and glutamate, and it's hard to have more polar opposite functions in the brain than those two. What I'm trying to say is that minor differences in chemical structure can have enormous impacts on function. That said, it doesn't necessarily mean that they always *do*, so you may be on to something.

IIRC, tyrosine is a dopamine precursor (it's what dopamine is made from), so it can help to restore proper dopamine levels in the brain. Where did the tyrosine thing come from, though?